difficult if not impossible to make, you might consider a push fit
fitting for your final connection.

With it being a flat, I'm slightly nervous about having compression or push
fit joints under the floor, especially since it will be tiled upon and a
right b*****d to lift at a later date. I was planning on having pretty much
all the plumbing boxed in above the tiles (so my task with these water pipes
is to get them popping through the floor at a convenient point, from which
point I can feed them 'round to the shower, bath etc.). Hence wanting to
make it a solder connection if possible, although know what you mean - might
be difficult to get a dry piece of pipe to start on - here's hoping! :-)

Andy